Introduce WebPassOwnPtr.

public/platform/WebPrivateOwnPtr.h

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 18 matching lines @@
 
 #include "WebCommon.h"
 #include "WebNonCopyable.h"
 
 #if INSIDE_BLINK
 #include "wtf/PassOwnPtr.h"
 #endif
 
 namespace blink {
 
+template <typename T>
+class WebPrivatePassOwnPtr {
+public:
+    WebPrivatePassOwnPtr() : m_ptr(nullptr) {}
+    WebPrivatePassOwnPtr(decltype(nullptr)) : m_ptr(nullptr) {}
+    template <typename U>
+    WebPrivatePassOwnPtr(const WebPrivatePassOwnPtr<U>& o)

[kinuko, 2015/07/16 05:58:57]

Do we need this?

[yhirano, 2015/07/16 06:37:48]

Yes, if we pass a WebPrivatePassOwnPtr<Derived> to a function that takes a
WebPrivatePassOwnPtr<Base>. I think it is likely to happen.

+    {
+        m_ptr = o.m_ptr;
+        o.m_ptr = nullptr;
+    }
+    ~WebPrivatePassOwnPtr() { BLINK_ASSERT(!m_ptr); }
+    WebPrivatePassOwnPtr& operator =(const WebPrivatePassOwnPtr&) = delete;
+
+    T* get() const { return m_ptr; }

[kinuko, 2015/07/16 05:58:57]

Do we need this? I feel release() (in the other patch) and the assertion in the
dtor are all we need in our use case?

[yhirano, 2015/07/16 06:37:48]

Done.

+
+    template <typename U> friend class WebPrivateOwnPtr;
+    template <typename U> friend class WebPrivatePassOwnPtr;
+    template <typename U> friend WebPrivatePassOwnPtr<U> adoptWebPtr(U*);
+
+private:
+    explicit WebPrivatePassOwnPtr(T* ptr) : m_ptr(ptr) {}
+
+    mutable T* m_ptr;
+};
+
+template <typename T>
+WebPrivatePassOwnPtr<T> adoptWebPtr(T* p) { return WebPrivatePassOwnPtr<T>(p); }
+
 // This class is an implementation detail of the WebKit API.  It exists
 // to help simplify the implementation of WebKit interfaces that merely
 // wrap a pointer to a WebCore class. It's similar to WebPrivatePtr, but it
 // wraps a naked pointer rather than a reference counted.
 // Note: you must call reset(0) on the implementation side in order to delete
 // the WebCore pointer.
 template <typename T>
 class WebPrivateOwnPtr : public WebNonCopyable {
 public:
     WebPrivateOwnPtr() : m_ptr(nullptr) {}
     WebPrivateOwnPtr(decltype(nullptr)) : m_ptr(nullptr) {}
+    template <typename U>
+    WebPrivateOwnPtr(const WebPrivatePassOwnPtr<U>& o)

[kinuko, 2015/07/16 05:58:57]

Do we actually use this?

[yhirano, 2015/07/16 06:37:48]

Deleted.

+    {
+        m_ptr = o.m_ptr;
+        o.m_ptr = nullptr;
+    }
     ~WebPrivateOwnPtr() { BLINK_ASSERT(!m_ptr); }
 
-    explicit WebPrivateOwnPtr(T* ptr)
-        : m_ptr(ptr)
-    {
-    }
+    explicit WebPrivateOwnPtr(T* ptr) : m_ptr(ptr) {}
 
     T* get() const { return m_ptr; }
 
 #if INSIDE_BLINK
     template<typename U> WebPrivateOwnPtr(const PassOwnPtr<U>&, EnsurePtrConvertibleArgDecl(U, T));
 
     void reset(T* ptr)
     {
         delete m_ptr;
         m_ptr = ptr;
@@ skipping 26 matching lines @@
 template<typename T> template<typename U> inline WebPrivateOwnPtr<T>::WebPrivateOwnPtr(const PassOwnPtr<U>& o, EnsurePtrConvertibleArgDefn(U, T))
     : m_ptr(o.leakPtr())
 {
     static_assert(!WTF::IsArray<T>::value, "Pointers to array must never be converted");
 }
 #endif
 
 } // namespace blink
 
 #endif